This request is for funds to acquire a wide bore 750 MHz nuclear magnetic resonance (NMR) spectrometer for solid-state investigations of membrane proteins, macromolecular assemblies, and protein aggregates. Solid-state NMR (SSNMR) is an essential tool for understanding the structures and dynamics of proteins that are embedded within biological membranes or that form large aggregates and assemblies. An advantage of SSNMR, over other structural methods, is that it does not require proteins to form crystals or be soluble, and can be conducted on protein assemblies greater than 100 kD in size. The proposed acquisition addresses the expanding needs of multiple researchers at the University of Pittsburgh and their collaborators across multiple universities, as the lack of dedicated high-field SSNMR instrumentation in the greater Pittsburgh area is increasingly limiting their research on multiple biomedical fronts. The new instrument will be housed in the state-of-the art NMR facility in the Department of Structural Biology at the University of Pittsburgh - part of a recently established Department of Structural Biology at the School of Medicine. The instrument will serve the needs of scientists in multiple collaborative networks, including the NIH-supported Pittsburgh Center for HIV Protein Interactions (PCHPI). Its incorporation into a pre-existing and otherwise well-equipped research center will ensure optimal usage of this cutting-edge instrument. The major users of the requested instrument will be at the University of Pittsburgh School of Medicine and the University of Delaware, with additional users at Carnegie Mellon University, Bucknell University and elsewhere (12 groups in total). Multiple NIH-funded research projects will benefit from the availability of this dedicated high-field solid-state NMR spectrometer, including studies of proteins and protein assemblies involved in HIV-cellular protein interactions, neurodegenerative disorders, neurotransmitter and hormone receptors, as well as cellular trafficking. The instrument will be fully outfitted for multidimensional spectroscopy in the solid state, specifically for 3D structure determination and dynamics analysis of uniformly, extensively and selectively isotopically (13C, 15N, 2H, 19F) enriched proteins, peptides, and macromolecular assemblies. The instrument will be equipped with low temperature setup and probes, permitting investigations of protein folding and reaction intermediates as well as comprehensive dynamics studies, at enhanced sensitivity. The probes and the dual receiver capabilities will enable development of novel experiments and data acquisition protocols to facilitate studies of large proteins and protein assemblies. This 750 MHz SSNMR instrument will have an immediate impact on the infrastructure at the University of Pittsburgh and participating institutions as it will enable cutting-edge science, will foster highl collaborative biomedical research, and will support the vibrant research environment in the State of Pennsylvania.